The present invention relates to the chain tensioner arts. The preferred embodiment of the invention finds particular application in conjunction with a timing chain drive for an automotive engine, and will be described with reference thereto. However, the present invention can also find application with other types of chain drive systems, and in applications other than automotive engines.
With reference to FIG. 1, a conventional chain drive system 10, of the type often used on internal combustion automobile engines for timing purposes, rotates in a clockwise direction as shown by arrow 11. The chain drive system 10 includes at least a drive sprocket 12, a driven sprocket 14, and a chain 16 (e.g. roller chain, inverted tooth chain, etc.) having a number of chain pitches 18. As known in the art, the chain drive system 10 can include additional sprockets such as idler sprockets, balance shaft sprockets, etc. The chain 16 engages and wraps about sprockets 12 and 14 and has two spans extending between the sprockets, slack strand 20 and taut strand 22. A central portion of the taut strand 22 may be guided between the driven sprocket 14 and the drive sprocket 12 with a conventional chain guide (not shown). The taut strand 22 of chain 16 is under tension as s shown by arrow 26.
A conventional blade-type mechanical tensioner assembly 24 applies a tensioning force to the slack strand 20. The tensioner assembly 24 includes a bracket 28, typically formed by stamping as a rigid metal bracket, and an elongated shoe sub-assembly 30 pivotally secured to the bracket 28 by a pivot pin 32. The sub-assembly 30 includes a chain-engaging shoe member 34, typically injection molded from a plastic resin material that will xe2x80x9ccreepxe2x80x9d under load and elevated temperature, and a blade spring 36, typically formed from spring steel, incorporated into the shoe member to provide the shoe sub-assembly 30 with the resiliency and rigidity that is necessary to apply the proper amount of tensioning force to the slack strand 20 of chain 16.
As best shown in FIGS. 2a and 2b, the pivot pin 32 includes a flanged portion 32A having a cylindrical portion 32B. The bracket 28 includes an aperture 33 that is shaped to mutually conform to and receive the cylindrical portion 32B. The pivot pin 32 can be affixed to the bracket 28 in any conventional manner such as by resistance welding, press-fitting, swaging, etc. The pivot pin 32 provides a reaction support and pivoting means for the shoe sub-assembly 30, thus permitting the tensioner to function properly in a firing engine. The pin 32, as illustrated in FIGS. 2b and 2c, does not extend beyond an engine mounting surface 38 of the bracket. However, at least two fasteners 40A, 40B (FIG. 1) extend past the engine mounting surface 38 to secure the bracket 28 to an engine case or block in order to properly orient the chain-engaging shoe member 34 with respect to the slack strand 20 of the chain 16.
With many engine designs, the above-described tensioner assembly 24 must be installed within a confined space, thus making it difficult to utilize multiple fasteners to secure the tensioner assembly to the engine. Accordingly, it is considered desirable to provide a new and improved chain tensioner assembly, that meets the above-stated needs and overcomes the foregoing difficulties and others while providing better and more advantageous results.
In accordance with one aspect of the present invention, a chain tensioner assembly is provided. The chain tensioner assembly includes a bracket having a first surface and a second surface, and a pivot pin secured to the bracket. The pivot pin includes a first portion extending from the first surface and a second portion extending from the second surface. A shoe sub-assembly is pivotally mounted to the pivot pin first portion. The pivot pin second portion is adapted to extend into a bore of an associated engine component in a mounted state of the chain tensioner assembly.
In accordance with another aspect of the present invention, a chain drive system is provided. The chain drive system includes a first sprocket, a second sprocket, a chain adapted to engage the first sprocket and the second sprocket, and a chain tensioner assembly adapted to impart a tensioning force on the chain. The chain tensioner assembly includes a bracket having a first surface and a second surface, and a pivot pin secured to the bracket. The pivot pin includes a first portion extending from the first surface and a second portion extending from the second surface. A shoe subassembly is pivotally mounted to the pivot pin first portion. The pivot pin second portion is adapted to extend into a bore of an associated engine component in a mounted state of the chain tensioner assembly.
In accordance with a further aspect of the present invention, a chain drive system associated with an automobile engine is provided. The chain drive system includes a drive sprocket rotatably mounted to the engine, a driven sprocket rotatably mounted to the engine, a chain engaging the drive sprocket and the driven sprocket, and a chain tensioner assembly that imparts a tensioning force on the chain. The chain tensioner assembly includes a bracket having a first surface and a second surface, and a pivot pin secured to the bracket. The pivot pin includes a first portion extending from the first surface and a second portion extending from the second surface. A shoe sub-assembly is pivotally mounted to the pivot pin first portion. The pivot pin second portion extends into a bore associated with the engine.
In accordance with yet another aspect of the present invention, a method of mounting a chain tensioner assembly to an engine component is disclosed. The chain tensioner assembly includes a bracket having a first surface and a second surface, and a pivot pin secured to the bracket. The pivot pin includes a first portion extending from the first surface and a second portion extending from the second surface. A shoe sub-assembly is pivotally mounted to the pivot pin first portion. The method includes the steps of inserting the pivot pin second portion into a bore associated with the engine component, and securing the bracket to the engine component with a fastener.
One advantage of the present invention is the provision of a chain tensioner assembly that will package in a confined space where two or more fasteners cannot be easily utilized.
Another advantage of the present invention is the provision of a chain tensioner assembly that can be easily and rapidly secured to an engine component such as an engine block during an assembly procedure.
Yet another advantage of the present invention is the provision of a method for mounting a chain tensioner assembly within a confined space associated with an automotive engine component such as an engine block, where it is difficult to utilize a plurality of conventional fasteners to attach the chain tensioner assembly to the engine component.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiment.